Required Practicals Flashcards
(12 cards)
Neutralisation Equipment
- 50cm cubed burette plus stand and burette holder
- 2 x 250cm cubed beaker
- 250cm cubed conical flask
- 25.0cm cubed bulb pipette plus pipette filler
- white tile
- funnel
- phenolphthalein indicator
- 0.050 mol/dm cubed sufuric acid
- sodium hydroxide of unknown concentration
- wash bottle of distilled water
Neutralisation Equation
H2SO4(aq)+2NaOH(aq) = Na2SO4(aq) + 2H2O(I)
Neutralisation Method
1) Use a clean, dry pipette and pipette filler to measure exactly 25.0cm cubed of sodium hydroxide solution into a conical flask
2) Place the flask on a white tile
3) Add three or four drops of phenolphthalein indicator to the flask
4) Prepare and fill the burette with dilute 0.050 mol/dm cubed sulfuric acid and record the initial volume in a results table
5) Titrate the sulfuric acid with sodium hydroxide swirling the flask on addition
6) When the indicator changes colour, record the volume of acid added
7) Repeat the titration accurately by adding the acid drop wise near the end point. Make sure you record the initial and final burette readings in the appropriate column in the table
8) Repeat the accurate titrations until you have two concordant results (within 0.10 cm cubed of each other).
Making a Copper Salt Equipment
- 25cm cubed measuring cyclinder
- 100cm cubed beaker
- Spatula
- Filter funnel and paper
- Glass rod
- 250cm cubed beaker
- Bunsen burner, heat proof mat, tripod, gauze
- Evaporating basin
- Conical flask
- Tongs
- 20cm cubed 1mol/dm cubed sulfuric acid
- Copper(II) oxide powder
Making a copper salt - Method
Using a measuring cylinder, measure 20cm cubed of acid into the beaker.
2 Stand the beaker on a tripod and gauze and warm gently until it is almost boiling. Turn off the Bunsen burner.
3 Add half a spatula of copper(II) oxide power into the acid and stir using the glass rod.
4 Continue adding the copper(II) oxide until no more dissolves. When the copper(II) oxide disappears the solution is clear blue.
5 Allow the apparatus to cool completely and then filter the mixture and discard the residue.
6 Pour the filtrate into an evaporating basin. Evaporate this gently using a water bath (250cm cubed beaker with boiling water) on the tripod and gauze (see diagram). Stop heating once crystals start to form.
7 Remove the evaporating basin from the heat and leave to crystallise.
Making a Salt - Equation
CuO(s) + H2SO4(aq) = CuSO4(aq) + H2O(l)
Copper oxide + sulfuric acid = Copper sulfate + water
Electrolysis - Equipment
- 1 beaker with electrodes
- Retort stand and clamp to hold electrodes
- DC power supply (6 V)
- 2 x leads
- 2 x crocodile clips
- 1mol/dm cubed copper (II) chloride
- 1 mol/dm cubed potassium bromide
- 1mol/dm cubed sodium sulfate
- blue litmus paper
- splints & candle
Electrolysis - Method
1 Set up the apparatus as shown in the diagram.
2 Fill the beaker with potassium bromide solution
ensuring that the electrodes are covered.
3 Fill two test tubes with potassium bromide solution and
covering the mouth of test tube with your index finger,
invert the filled tubes over each electrode.
4 Set up the circuit and turn on the current (6V).
5 After a few minutes, record what you see at the two
electrodes in the results table below.
6 Test any gases produced with damp blue litmus paper.
7 Rinse out the beaker and test tubes and repeat the
experiment using the other solutions.
Electrolysis - Half Equations
Cu 2+ + 2e- = Cu
Na+ + e- = Na
2H+ + 2e- = H2
2Cl- = Cl2 + 2e-
2OH- = O2 + 2e-
Effect of Concentration on Rate 2 - Method
1) Collect a clean 100 cm cubed beaker. Use this beaker to collect and store 0.20 mol/dm thiosulfate solution.
2) For the first experiment, measure out 10 cm cubed of the sodium thiosulfate solution into a conical flask using a measuring cylinder and add 40 cm cubed of deionised water. (You can use
the same 50 cm cubed measuring cylinder for the water and the sodium thiosulfate)
3) Place the flask on a piece of paper marked with a cross.
4) Measure out 10 cm cubed of hydrochloric acid using a 10 cm cubed measuring cylinder.
5) When you are ready add the acid to the sodium thiosulfate in the flask and start the stopwatch.
6) Swirl the flask well and time how long it takes to become too cloudy to see the cross.
7) Clean the flask out thoroughly and then move on to the next experiment using different volumes of sodium thiosulfate and water in order to change its concentration.
Effect of Concentration on Rate 2 - Equation
Na2S2O3(aq) + 2 HCl(aq) = 2 NaCl(aq) + S(s)+SO2(g)+H2O(l)
Temperature Rise -Method
1 Use a measuring cylinder to put 25 cm polystyrene cup.
2 Weigh out 0.5 g of zinc powder in a weighing bottle (or on a weighing boat) – remember to take the bottle/boat off the balance when you add zinc.
3 Record the temperature of the copper sulfate solution in a suitable table.
4 Now tip the zinc into the copper sulfate solution, put the lid on the cup and stir well with the thermometer. Enclose the thermometer within a tripod to stop the cup and thermometer falling over.
5 Keep stirring until the temperature reaches a maximum. Record the highest temperature and find the temperature rise.
6 Empty the polystyrene cup by swirling and tipping into the bowl for waste (“swirl & tip” – the better the swirl and the shorter the time between the swirl and tip the better). You may need to rinse further with water.
7 You are going to repeat this experiment with 1.0, 1.5, 2.0 and 2.5 g of zinc. Use the same polystyrene cup each time.
